Lactate dehydrogenase-catalyzed stereospecific hydrogen atom transfer from reduced nicotinamide adenine dinucleotide to dicarboxylate radicals

Journal Article · Thu Sep 25 04:00:00 EDT 1975 · J. Biol. Chem.; (United States)

OSTI ID:7292997

Chan, P C; Bielski, B H.J.

The dicarboxylate radical was generated in an N/sub 2/O-saturated fumarate solution by high energy ionizing radiation. When NADH was present in the solution, product analysis indicated a stoichiometry of 2 molecules of the radical reacted with 1 NADH molecule to form 2 malate and 1 enzymatically active NAD/sup +/ molecules. In a similar experiment using tritium label on position A of NADH, due to an isotope effect, only 10 percent of the label was transferred to malate; most of the remaining tritium was found in the NAD/sup +/ formed. When lactate dehydrogenase was added, however, no label was detectable in NAD/sup +/, and over 80 percent of the tritium lost from NADH was found in malate. The stereospecific transfer of the hydrogen atom from lactate dehydrogenase-bound NADH to the dicarboxylate radical suggested that the free radical reaction must have taken place at the active site. The hydrogen atom transfer was inhibited by oxamate. Results from flow experiments in which an irradiated fumarate solution was mixed with a solution of lactate dehydrogenase and NADH are in support of a mechanism in which the hydrogen atom transfer occurs in the first oxidation step. (auth)

• Research Organization: State Univ. of New York Downstate Medical Center, Brooklyn
• OSTI ID: 7292997
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 250:18; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
COENZYMES
CRYOGENIC FLUIDS
DEHYDROGENASES
DICARBOXYLIC ACIDS
DIRECT REACTIONS
ELEMENTS
ENZYMES
FLUIDS
HYDROGEN
HYDROGEN ISOTOPES
ISOTOPES
KINETICS
LACTATE DEHYDROGENASE
LIGHT NUCLEI
NAD
NONMETALS
NUCLEAR REACTIONS
NUCLEI
NUCLEOTIDES
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDATION
OXIDOREDUCTASES
RADICALS
RADIOISOTOPES
REACTION KINETICS
STEREOCHEMISTRY
TRANSFER REACTIONS
TRITIUM
YEARS LIVING RADIOISOTOPES